Phase relation studies in the CeO_2-La_2O_3 system at 1100-1500 °C

摘要

Materials based on CeO_2-La_2O_3 system are promising candidates for a wide range of applications, but the phase relationship has not been studied systematically previously. To address this challenge, the subsection of the phase diagram for 1100 and 1500 °C have been elucidated. Samples of different compositions have been prepared from nitrate acid solutions using conventional ceramic techniques;;evaporation, drying, and calcinations. The phase relations in the binary CeO_2-La_2O_3 system at 1100-1500 °C were studied from the heat treated samples using X-ray diffraction analysis, petrographic investigation and scanning electron microscopy in the overall concentration range. It was established that in the binary Ce02-La203 system there exist fields of solid solutions based on hexagonal (A) modification of La_2O_3, and cubic modification of CeO_2 with fluorite-type structure (F). The systematic study that covered whole composition range excluded formation of new phases. The refined lattice parameter of the unit cell and the boundaries of the homogeneity fields for solid solutions were determined.